Insect growth regulating composition

ABSTRACT

A microencapsulated insect growth regulating composition comprising an insect growth regulation active ingredient in a wall formed of polyurethane or polyurea, having an average particle diameter of 1 to 40 μm, a wall thickness of 0.005 to 0.5 μm, a ratio of a wall thickness/an average particle diameter of 0.0003 to 0.003, and a volume ratio of microencapsulated particles having a particle diameter of not less than 50 μm of not more than 20% by volume based on a total volume of microencapsulated particles sufficiently exerts efficacy of the active ingredient, i.e., the insect growth regulation activity.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a microencapsulated insect growthregulating composition.

2. Prior Art

A poisonous bait composition in which an insect growth regulating activeingredient is microencapsulated is known in U.S. Pat. No. 5,300,293.

The composition has not sufficient efficacy when used in agriculturalfields, apart from a poisonous bait of a cockroach.

SUMMARY OF THE INVENTION

The present invention provides a microencapsulated insect growthregulating composition comprising an insect growth regulating activeingredient, wherein efficacy of the insect growth regulating activeingredient as an active ingredient is sufficiently exerted,particularly, in agricultural fields.

In order to achieve this object, the present invention makes efficacy ofan insect growth regulation active ingredient to be sufficiently exertedby adopting an average particle diameter, a wall thickness, a ratio ofwall thickness/average particle diameter of microcapsules, and a volumeratio of microcapsule particles of 50 μm or larger in a specified range.

That is, the present invention is:

1. A microencapsulated insect growth regulating composition, whichcomprises an insect growth regulating active ingredient encapsulated ina wall formed of polyurethane or polyurea, having an average particlediameter of 1 to 40 μm, a wall thickness of 0.005 to 0.5 μm, and a ratioof wall thickness/average particle diameter of 0.0003 to 0.003, whereina volume ratio of microencapsulated particles having a particle diameterof not less than 50 μm is not more than 20% by volume based on a totalvolume of microcapsule particles.

2. The insect growth regulating composition according to 1, wherein theinsect growth regulating active ingredient is an insect juvenilehormone-like compound.

3. The insect growth regulating composition according to 1, wherein theinsect growth regulating active ingredient is 4-phenoxyphenyl2-(2-pyridyloxy)propyl ether.

4. Use of an insect growth regulating composition according to any oneof 1 to 3 for controlling an insect pest.

5. A method for controlling an insect pest comprising applying aneffective amount of an insect growth regulating composition according toany one of 1 to 3 directly to an insect pest or to a place where aninsect pest inhabits.

DETAILED DESCRIPTION OF THE INVENTION

The insect growth regulating composition of the present invention ischaracterized by a microencapsulated insect growth regulatingcomposition, which comprises an insect growth regulating activeingredient encapsulated in a wall formed of a polyurethane or apolyurea, having an average particle diameter of 1 to 40 μm, a wallthickness of 0.005 to 0.5 μm, and a ratio of wall thickness/averageparticle diameter of 0.0003 to 0.003, wherein a volume ratio ofmicroencapsulated particles having a particle diameter of not less than50 μm is not more than 20% by volume based on a total volume ofmicrocapsule particles.

The insect growth regulating composition of the present invention can beprepared, for example, by the following method.

First, an insect growth regulating ingredient and a polyvalentisocyanate are mixed to obtain an oil phase. At this time, a hydrophobicoil solvent may be added to the organic phase, if necessary. Theresulting oil phase is dispersed by mixing with an aqueous phasecontaining a dispersant (dispersing step), and a polyhydric alcohol or apolyvalent amine is added to the dispersion, to perform a microcapsuleforming reaction (microencapsulating reaction step). The reactiontemperature of this microencapsulating reaction step is usually in arange of 20 to 85° C., and the reaction time is usually in a range of 1to 90 hours.

In the aforementioned microencapsulating reaction step, when apolyhydric alcohol is used, a microencapsulated product having apolyurethane wall is obtained and, when a polyvalent amine is used, amicroencapsulated product having a polyurea wall is obtained.

When a microencapsulating reaction step is performed using a polyhydricalcohol, an oil phase may be dispersed in an aqueous phase in which thepolyhydric alcohol is mixed, in place of dispersing an oil phase into anaqueous phase, and then adding the polyhydric alcohol.

Alternatively, a microencapsulating reaction step may be performedwithout adding a polyhydric alcohol or a polyvalent amine. In this case,a microencapsulated product having a polyurea wall is obtained.

Examples of the dispersant used in the aforementioned process includewater-soluble polymers, and specific examples thereof include naturalpolysaccharides such as gum arabic, natural water-soluble polymers suchas gelatin and collagen, water-soluble semi-synthetic polysaccharidessuch as carboxymethylcellulose, methylcellulose, andhydroxypropylcellulose, and water-soluble synthetic polymers such aspolyvinyl alcohol, and polyvinylpyrrolidone.

Examples of the polyvalent isocyanate used in the aforementioned processinclude an adduct of trimethylolpropane and toluenediisocyanate, anadduct of trimethylolpropane and hexamethylenediisocyanate,hexamethylenediisocyanate trimer having a biuret bond, and polyvalentisocyanate having an isocyanurate structure.

Examples of the polyhydric alcohol used upon formation of a polyurethanewall include ethylene glycol, propylene glycol, butylene glycol, andcyclopropylene glycol.

Examples of the polyvalent amine used upon formation of a polyurea wallinclude ethylenediamine, hexamethylenediamine, diethylenetriamine, andtriethylenetetramine.

Examples of the hydrophobic organic solvent which is used in theaforementioned process as necessary include aromatic hydrocarbons, anddialkyl esters of aliphatic dicarboxylic acids.

Examples of the aromatic hydrocarbon include toluene, xylene,alkylbenzene, alkylnaphthalene, and phenylxylylethane, or a mixturethereof may also be used. As the aromatic hydrocarbon, commerciallyavailable solvents may be used as they are, and examples of such thecommercially available solvents include Hisol SAS-296 (mixture of1-phenyl-1-xylylethane and 1-phenyl-1-ethylphenylethane; trade name ofNIPPON OIL CORPORATION), Cactus Solvent HP-MN (methylnaphthalene 80%;trade name of JAPAN ENERGY CORPORATION), Cactus Solvent HP-DMN(dimethylnaphthalene 80%; trade name of JAPAN ENERGY CORPORATION),Cactus Solvent P-100 (alkylbenzene having 9 to 10 carbon atoms; tradename of JAPAN ENERGY CORPORATION), Cactus Solvent P-150 (alkylbenzene;trade name of JAPAN ENERGY CORPORATION), Cactus Solvent P-180 (mixtureof methylnaphthalene and dimethylnaphthalene; trade name of JAPAN ENERGYCORPORATION), Cactus Solvent P-200 (mixture of methylnaphthalene anddimethylnaphthalene; trade name of JAPAN ENERGY CORPORATION), CactusSolvent P-220 (mixture of methylnaphthalene and dimethylnaphthalene;trade name of JAPAN ENERGY CORPORATION), Cactus Solvent PAD-1(dimethylmonoisopropylnaphthalene; trade name of JAPAN ENERGYCORPORATION), Solvesso 100 (aromatic hydrocarbon; trade name ofEXXONMOBIL CORPORATION), Solvesso 150 (aromatic hydrocarbon; trade nameof EXXONMOBIL CORPORATION), Solvesso 200 (aromatic hydrocarbon; tradename of EXXONMOBIL CORPORATION), Swasol 100 (toluene; trade name ofMARUZEN PETEROCHEMICAL CO., LTD.), and Swasol 200 (xylene; trade name ofMARUZEN PETEROCHEMICAL CO., LTD.).

Examples of the dialkyl ester of aliphatic dicarboxylic acid includedialkyl adipates such as dibutyl adipate, and dioctyl adipate. As thealiphatic dicarboxylic acid diester, commercially available solvents maybe used as they are, and examples of such the commercially solventsinclude Vinycizer 40 (diisobutyl adipate; trade name of KAO CORPORATION)and Vinycizer 50 (diisodecyl adipate; trade name of KAO CORPORATION).

Thus, the microcapsules can be obtained as slurry containing them.

The microcapsules are used by formulating into various forms such asslurry, powder and granules. Usually, the microcapsules are used as aslurry composition in which the microcapsules are suspended in water,i.e., an aqueous suspension concentrate.

The aqueous suspension concentrate may further contain a preservativeand; various stabilizers, for example, a thickener, an antifreezingagent, and a specific gravity regulating agent.

Examples of the thickener used in the aqueous suspension concentrateinclude natural polysaccharides such as xanthan gum, rhamsan gum, locustbean gum, carrageenan and Welan gum, synthetic polymers such as sodiumpolyacrylate, semi-synthetic polysaccharides such ascarboxymethylcellulose, mineral fine powders such as aluminum magnesiumsilicate, smectite, bentonite, hectorite, and silica, and alumina sol,and 0 to 10% by weight of the thickener is generally contained in theaqueous suspension concentrate. Examples of the antifreezing agentinclude alcohols such as propylene glycol, and 0 to 20% by weight of theantifreezing agent is generally contained in the aqueous suspensionconcentrate. Examples of the specific gravity regulating agent includewater-soluble salts such as sodium sulfate, and water-solublefertilizers such as urea.

The insect growth regulating active ingredient used in the insect growthregulating composition of the present invention is not particularlylimited, but examples thereof include insect juvenile hormone-likecompounds such as dodecadienoate compounds, oximether compounds,pyridylether compounds, and carbamate compounds, and insect chitinformation inhibiting compounds such as benzoylphenylurea compounds.

Examples of such the insect growth regulation active ingredient will beshown below together with compound numbers.

-   (1) Isopropyl(2E-4E)-11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate    <methoprene>-   (2) Ethyl(2E-4E)-3,7,11-trimethyldodeca-2,4-dienoate <hydroprene>-   (3) 4-phenoxyphenyl 2-(2-pyridyloxy)propyl ether <pyriproxyfen>-   (4) Propionaldehyde oxime O-2-(4-phenoxyphenoxy)ethylether-   (5) Propionaldehyde oxime O-2-(4-phenoxyphenoxy)propylether-   (6) O-Ethyl N-[2-(4-phenoxyphenoxy)ethyl]carbamate <fenoxycarb>-   (7) 1-(4-Ethylphenoxy)-6,7-epoxy-3,7-dimethyl-2-octene <R-20458>-   (8) Prop-2-ynyl (±)-(E,E)-3,7,11-trimethyldodeca-2,4-dienoate    <kinoprene>-   (9) (E)-Z-(4-ethylphenoxy)-2,6-dimethyl-2,3-epoxy-6-octene    <ethoprene>-   (9) 1-(4-Chlorophenyl)-3-(2,6-difluorobenzoyl)urea <diflubenzuron>-   (10)    2-Chloro-N-[[[4-(trifluoromethoxy)-phenyl]amino]carbonyl]benzamide    <triflumuron>-   (11)    N-[[[5-(4-bromophenyl)-6-methyl-2-pyrazinyl]amino]carbonyl]-2,6-dichlorobenzamide    <EL 494>-   (12) 1-(3,5-Dichloro-2,4-difluorophenyl)-3-(2,6-difluorobenzoyl)urea    <teflubenzuron>-   (13)    1-[3,5-Dichloro-4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenyl]-3-(2,6-difluorobenzoyl)urea    <chlorfluazuron>p0 (14)    N-[[[3,5-dichloro-4-(1,1,2,2-tetrafluoroethoxy)phenyl]amino]carbonyl]-2,6-difluorobenzamide    <XRD-473>-   (15)    1-[4-(2-Chloro-α,α,α-trifluoro-p-tolyloxy)-2-fluorophenyl]-3-(2,6-difluorobenzoyl)urea    <flufenoxuron>-   (16)    1-[3,5-Dichloro-4-(1,1,2,2-tetrafluoroethoxy)phenyl]-3-(2,6-difluorobenzoyl)urea    <hexaflumuron>-   (17)    (R,S)-1-[2,5-dichloro-4-(1,1,2,3,3,3-hexafluoropropoxy)phenyl]-3-(2,6-difluorobenzoyl)urea    <lufenuron>-   (18)    (R,S)-1-[3-chloro-4-(1,1,2-trifluoro-2-trifluoromethoxyethoxy)phenyl]-3-(2,6-difluorobenzoyl)urea    <novaluron>-   (19)    1-(2,6-Difluorobenzoyl)-3-[2-fluoro-4-(1,1,2,2-tetrafluoroethoxy)phenyl]urea-   (20)    1-(2,6-Difluorobenzoyl)-3-(2-fluoro-4-trifluoromethylphenyl)urea-   (21)    2-Tert-butylimino-3-isopropyl-5-phenyl-1,3,5-thiadiazinane-4-one    <buprofezin>-   (22) N-cyclopropyl-1,3,5-triazine-2,4,6-triamine <cyromazine>-   (23) N-tert-butyl-N′-(4-ethylbenzoyl)-3,5-dimethylbenzohydrazide    <tebufenozide>-   (24) 2′-tert-Butyl-5-methyl-2′-(3,5-xyloyl)chroman-6-carbohydrazide    <chromafenozide>-   (25) N-tert-Butyl-N′-(3-methoxy-o-toluoyl)-3,5-xylohydrazide    <methoxyfenozide>-   (26) N-tert-Butyl-N′-(4-chlorobenzoyl)benzohydrazide <halofenozide>

Usually, 0.5 to 50% by weight of the insect growth regulating activeingredient is contained in the insect growth regulating composition ofthe present invention.

Then, an average particle diameter, a wall thickness, and a volume ratioof microencapsulated particles having a particle diameter of not lessthan 50 μm based on a total volume of microcapsules in the presentinvention will be explained. The average particle diameter in thepresent invention means a volume median diameter and, for example, avalue measured using a laser diffraction type particle size analyzer(specifically, for example, Mastersizer 2000 (product of MALVERNInstruments Ltd.)) can be adopted.

The wall thickness of microcapsules varies depending on a ratio ofvolumes of a core substance and a wall substance, and can be calculatedby the following approximate equation. That is, when Wc represents aweight of a core substance of the microcapsules, Ww represents a weightof a wall substance, ρw represents a density of a wall substance, ρcrepresents a density of a core substance, and d represents an averageparticle diameter of a core substance, the wall thickness is:Wall thickness=(Ww/Wc)×(ρc/ρw)×(d/6)The wall thickness referred in the present invention is calculated usingthis equation.

The volume ratio of microencapsulated particles having a particlediameter of not less than 50 μm based on a total volume of microcapsulescan be calculated from a volume distribution measured using, forexample, a laser diffraction type particle size analyzer (specifically,for example, Mastersizer 2000 (product of MALVERN Instruments Ltd.)).

In the insect growth regulating composition of the present invention,the average particle diameter is 1 to 40 μm, the wall thickness is 0.005to 0.5 μm, the ratio of wall thickness/average particle diameter is0.0003 to 0.003, and the volume ratio of microcapsule particles having aparticle diameter of not less than 50 μm is not more than 20% by volumebased on a total volume of microencapsulated particles.

In the present invention, microcapsules having an average particlediameter of 1 to 40 μm, a wall thickness of 0.005 to 0.5 μm, a ratio ofwall thickness/average particle diameter of 0.0003 to 0.003, and avolume ratio of microencapsulated particles having a particle diameterof not less than 50 μm of not more than 20% by volume based on a totalvolume of microencapsulated particles can be obtained, for example, byadjusting (1) a kind and a concentration of a dispersant dissolved in anaqueous phase, (2) a ratio of an aqueous phase and an oil phase, and/or(3) a dispersion manner, and a stirring intense at the time ofdispersing the oil phase in the aqueous phase, in the aforementioneddispersing step of the production process of the insect growthregulating composition of the present invention.

Specifically, for example, a kind and a concentration of a dispersant tobe dissolved in an aqueous phase are determined, an oil phase is mixedwith an aqueous phase at a volume ratio of 0.3 to 2 of the oil phaserelative to 1 of the aqueous phase, and the oil phase is dispersed inthe aqueous phase under appropriate operation conditions of a dispersingmachine. An average particle diameter of oil particles and a volumeratio of oil particles having a particle diameter of not less than 50 μmbased on a total volume of oil particles in the resulting dispersion aremeasured using a laser diffraction type particle size analyzer(specifically, for example, Mastersizer 2000 (product of MALVERNInstruments Ltd.)).

If the average particle diameter of oil particles in the dispersion thusobtained is less than 1 μm, a dispersion having a larger averageparticle diameter of oil particles can be obtained by modifying thedispersing step, such as by reducing the dispersant concentration,reducing the stirring intense at the time of dispersion of the oil phasein the aqueous phase, reducing the volume ratio of the oil phaserelative to the aqueous phase, and/or changing the dispersant. On theother hand, if the average particle diameter of oil particles in theresulting dispersion is larger than 40 μm, a dispersion having a smalleraverage particle diameter of oil particles can be obtained by modifyingthe dispersing step, such as by increasing the dispersant concentration,increasing the stirring intense at the time of dispersion of the oilphase in the aqueous phase, increasing the volume ratio of the oil phaserelative to the aqueous phase, and/or changing the dispersant.

If the volume ratio of oil particles having a particle diameter of notless than 50 μm based on a total volume of oil particles in thedispersion thus obtained is more than 20% by volume, a dispersion havingnot more than 20% by volume of the volume ratio of oil particles havinga particle diameter of not less than 50 μm based on a total volume ofoil particles can be obtained by modifying the dispersing step, such asby increasing the stirring speed of the dispersing machine, uniformlydispersing the entire dispersion, and/or changing the dispersant.

The properties of a particle diameter of oil particles in a dispersionare reflected in the properties of the microencapsulated particles ofthe microencapsulated composition obtained by the microencapsulatingstep.

Further, the wall thickness can be changed by adjusting amounts of thewall materials of microcapsules used for preparation of the insectgrowth regulating composition of the present invention, that is, theamounts of a polyvalent isocyanate and a polyhydric alcohol or apolyvalent amine, in particular, an amount of a polyvalent isocyanateaccording to an average particle diameter of oil particles in adispersion. Namely, first, the conditions of the dispersing step aredetermined so that an average particle diameter of oil particles in adispersion becomes 1 to 40 μm, and a volume ratio of oil particleshaving a particle diameter of not less than 50 μm based on a totalvolume of oil particles becomes not more than 20% by volume. After that,the amounts of a polyvalent isocyanate and a polyhydric alcohol or apolyvalent amine suitable for a predetermined wall thickness can bedetermined so that a ratio of wall thickness/average particle diameterbecomes 0.0003 to 0.003.

Examples of insects on which the insect growth regulating composition ofthe present invention exerts efficacy include as follows.

Hemiptera insect pests: planthoppers such as Laodelphax striatellus,Nilaparvata lugens, and Sogatella furcifera, leafhoppers such asNephotettix cincticeps, and Nephotettix virescens, aphids such as Aphisgossypii, Myzus persicae, Aphis citricola, Lipaphis pserudobrassicae,Nippolachnus piri, Toxoptera aurantii, and Toxoptera ciidius, stink bugssuch as Nezara antennata, Cletus punctiger, Riptortus clavetus, andPlautia stali, whiteflies such as Trialeurodes vaporariorum, Bemisiatabaci, and Bemisia argentifolii, scales such as Aonidiella aurantii,Comstockaspis perniciosa, Unaspis citri, Pseudaulacaspis pentagona,Saissatie oleae, Lepidosaphes beckii, Ceroplastes rubens, and Iceryapurchasi, lace bugs, and psyllids.

Lepidoptera insect pests: pyralid moths such as Chilo suppressalis,Cnaphalocrocis medinalis, Ostrinia nubilalis, Hellulla undalis,Parapediasia terrella, Notarcha derogata, and Plodia interpunctella,noctuid moths such as Spodoptera litura, Pseudaletia separata, Mamestrabrassicae, Agrotis ipsilon, Thoricoplusia spp., Heliothis spp., andHelicoverpa spp., whites and sulfer batterflies such as Pieris rapae,tortricid moths such as Adoxophyes spp., Grapholita molesta, and Cydiapomonolla, Carposinidae such as Carposina niponensis, lyonetiid mothssuch as Lyonetia spp., tussock moths such as Lymantriidae, and Euproctisspp., Yponomeutidae such as Plutella xylostella, Gelechiidae such asPectinophora gossypiella, Arctiidae such as Hyphantria cunea, andTineidae such as Tinea translucens, and Tineola bisselliella.

Diptera insect pests: mosquitoes such as Culex pipiens pallens, andCulex tritaeniorhynchus, Aedes spp. such as Aedes aegypti, and Aedesalbopictus, Anopheles spp. such as Anopheles sinensis, midges, houseflies such as Musca domestica, and Muscina stabulans, Calliphoridae,Sarcophagidae, anthomyiid flies such as lesser housefly, Delia platura,and Delia antiqua, clam flies such as Liriomyza trifolii, fruit flies,flea flies, small fruit flies, moth flies, Tabanidae, black flies, andstable flies.

Coleoptera insect pests: corn rootworm such as Diabrotica virgifera, andDiabrotica undecimpunctata howardi, scarabas such as Anomala cuprea, andAnomala rufocuprea, weevils such as Sitophilus zeamais, Lissorhoptrusoryzophilus, Hypera pastica, and Callosobruchuys chienensis, darklingbeetles such as Tenebrio molitor, and Tribolium castaneum, leaf beetlessuch as Aulacophora femoralis, Phyllotreta striolata, and Leptinotarsadecemlineata, Epilachna spp. such as Epilachna vigintioctopunctata,false powderpost beetles, Paederus fuscipes.

Thysanoptera insect pests: Thrips palmi, Thrips tabaci, Thripshawaiiensis, Scirtothrips dorsalis, Franklinie llaintonsa, Frankliniellaoccidentalis, and Ponticulothrips diospyrosi.

Hymenoptera insect pests: ants, Vespidae, Bethylidae, and Tenthredinidaesuch as Athalia japonica.

Orthoptera insect pests: mole crickets, and grasshoppers.

Aphaniptera insect pests: Ctenocephalides felis, Ctenocephalides canis,and Pulex irritans.

The insect growth regulating composition of the present invention isparticularly effective for controlling, inter alia, scales, whiteflies,psyllids, tortricid moths, and Carposinidae.

When the insect growth regulating composition of the present inventionis used for controlling insect pests, for example, the insect growthregulating composition of the present invention having a concentrationof an insect growth regulation active ingredient of 0.001 to 10,000 ppmis applied by scattering directly to insect pests or plant and/or soilon which insect pests can inhabit, at a ratio of about 0.1 to 1,000g/1,000 m², preferably about 1 to 100 g/1,000 m² as an amount of aninsect growth regulation active ingredient.

That is, the insect growth regulating composition of the presentinvention is used in an insect pest controlling method of applying aneffective amount of the insect growth regulating composition of thepresent invention directly to an insect pest or to a place where aninsect pest inhabits.

The present invention will be explained in more detail below by way ofPreparation Examples and Test Examples, but the present invention is notlimited to these examples.

PREPARATION EXAMPLE 1

An oil phase was prepared by mixing 96.6 g of pyriproxyfen, 100 g ofHisol SAS-296 (a mixture of 1-phenyl-1-xylylethane and1-phenyl-1-ethylphenylethane; manufactured by NIPPON OIL CORPORATION),and 50 g of Vinycizer 40 (diisobutyl adipate; manufactured by KAOCORPORATION) and adding 2.4 g of Sumidur N-3300 (isocyanurate typepolyvalent isocyanate; manufactured by SUMIKA BAYER URETHANE CO., LTD.)thereto.

On the other hand, an aqueous phase was prepared by mixing 17.5 g of gumarabic, 40 g of ethylene glycol, and 344.4 g of ion-exchanged water.

The oil phase and the aqueous phase were mixed, and this mixture wasdispersed at room temperature for 5 minutes with T.K. Autohomomixer(homogenizer manufactured by TOKUSHU KIKA KOGYO CO., LTD.; number ofrevolution: about 6,100 rpm). Then, the dispersion was mildly stirred at75° C. for 48 hours to obtain microcapsule slurry. The microcapsules inthe resulting microcapsule slurry had an average particle diameter of19.5 μm, a wall thickness of 0.031 μm, a ratio of wall thickness/averageparticle diameter of 0.0016, and a volume ratio of microencapsulatedparticles having a particle diameter of not less than 50 μm based on atotal volume of microencapsulated particles of 1.3% by volume.

Then, the aforementioned microcapsule slurry was mixed with a thickenersolution obtained by mixing 1.5 g of xanthan gum, 3 g of aluminummagnesium silicate, 50 g of propylene glycol and 292.5 g ofion-exchanged water to obtain the insect growth regulating compositionof the present invention containing 9.7% by weight of pyriproxyfen(average particle diameter: 19.5 μm, wall thickness: 0.031 μm, wallthickness/average particle diameter: 0.0016, volume ratio ofmicroencapsulated particles having particle diameter of not less than 50μm based on total volume of microencapsulated particles: 1.3% byvolume).

PREPARATION EXAMPLE 2

The insect growth regulating composition of the present invention wasobtained according to the same manner as that of Preparation Example 1,except that 0.96 g of Sumidur N-3300 was used, a number of revolution ofT.K. Autohomomixer (homogenizer manufactured by TOKUSHU KIKA KOGYO CO.,LTD.) at dispersion was about 5,000 rpm, and a thickener solution mixedwith the microcapsule slurry was a mixture of 1.5 g of xanthan gum, 3 gof aluminum magnesium silicate, 50 g of propylene glycol and 293.5 g ofion-exchanged water (average particle diameter: 28.8 μm, wall thickness:0.018 μm, wall thickness/average particle diameter: 0.0006, volume ratioof microencapsulated particles having particle diameter of not less than50 μm based on total volume of microencapsulated particles: 11.4% byvolume).

PREPARATION EXAMPLE 3

The insect growth regulating composition of the present invention wasobtained according to the same manner as that of Preparation Example 1except that 3.36 g of Sumidur N-3300 was used, a number of revolution ofT.K. Autohomomixer (homogenizer manufactured by TOKUSHU KIKA KOGYO CO.,LTD.) at dispersion was about 6,100 rpm, and a thickener solution mixedwith a microcapsule slurry was a mixture of 1.5 g of xanthan gum, 3 g ofaluminum magnesium silicate, 50 g of propylene glycol and 291.5 g ofion-exchanged water (average particle diameter: 17.3 μm, wall thickness:0.038 μm, wall thickness/average particle diameter: 0.0022, volume ratioof microencapsulated particles having particle diameter of not less than50 μm based on total volume of microencapsulated particles: 0.8% byvolume)

PREPARATION EXAMPLE 4

An oil phase was prepared by mixing 96.6 g of pyriproxyfen, and 150 g ofVinycizer 40 (diisobutyl adipate; manufactured by KAO CORPORATION), andadding 1.0 g of Sumidur L-75 (adduct of trimethylolpropane andtoluenediisocyanate; manufactured by SUMIKA BAYER URETHANE CO., LTD.)thereto.

On the other hand, an aqueous phase was prepared by mixing 17.5 g of gumarabic, 40 g of ethylene glycol, and 344.4 g of ion-exchanged water.

The oil phase and the aqueous phase were mixed, and this mixture wasdispersed at room temperature for 5 minutes with T.K. Autohomomixer(homogenizer manufactured by TOKUSHU KIKA KOGYO CO., LTD; number ofrevolution: about 4,800 rpm). Then, the dispersion was mildly stirred at75° C. for 48 hours to obtain microcapsule slurry. The microcapsules inthe resulting microcapsule slurry had an average particle diameter of 33μm, a wall thickness was 0.012 μm, a wall thickness/an average particlediameter was 0.0036, and a volume ratio of microencapsulated particleshaving a particle diameter of not less than 50 μm based on a totalvolume of microencapsulated particles was 17.6% by volume.

Then, a thickener solution obtained by mixing 1.5 g of xanthan gum, 3 gof aluminum magnesium silicate, 50 g of propylene glycol and 292.5 g ofion-exchanged water, and the microcapsule slurry were mixed to obtainthe insect growth regulating composition of the present inventioncontaining 9.7% by weight of pyriproxyfen (average particle diameter: 33μm, wall thickness: 0.012 μm, wall thickness/average particle diameter:0.00036, volume ratio of microencapsulated particles having particlediameter of not less than 50 μm based on total volume ofmicroencapsulated particles: 17.6% by volume).

REFERENCE PREPARATION EXAMPLE

An oil phase was prepared by mixing 96.6 g of pyriproxyfen, 100 g ofHisol SAS-296 (mixture of 1-phenyl-1-xylylethane and1-phenyl-1-ethylphenylethane; manufactured by NIPPON OIL COMPANY), and50 g of Vinycizer 40 (diisobutyl adipate; manufactured by KAOCORPORATION), and adding 1.0 g of Sumidur L-75 (adduct oftrimethylolpropane and toluenediisocyanate; SUMIKA BYEL URETHANE CO.,LTD.) thereto.

On the other hand, an aqueous phase was prepared by mixing 17.5 g of gumarabic, 40 g of ethylene glycol, and 344.4 g of ion-exchanged water.

The oil phase and the aqueous phase were mixed, and this mixture wasdispersed at room temperature for 5 minutes with a T.K. Autohomomixer(homogenizer manufactured by TOKUSHU KIKA KOGYO CO., LTD.; number ofrevolution: about 4,300 rpm). Then, the dispersion was mildly stirred at75° C. for 48 hours to obtain microcapsule slurry. The microcapsules inthe obtained microcapsule slurry had an average particle diameter of39.5 μm, a wall thickness of 0.014 μm, a wall thickness/an averageparticle diameter of 0.00035, and a volume ratio of microencapsulatedparticles having a particle diameter of not less than 50 μm based on atotal volume of microencapsulated particles of 30.2% by volume.

Then, a thickener solution obtained by mixing 1.5 g of xanthan gum, 3 gof aluminum magnesium silicate, 50 g of propylene glycol and 293.5 g ofion-exchanged water, and the microcapsule slurry were mixed to obtain aninsect growth regulating composition containing 9.7% by weight ofpyriproxyfen (average particle diameter: 39.5 μm, wall thickness: 0.014μm, wall thickness/average particle diameter: 0.0004, volume ratio ofmicroencapsulated particles having particle diameter of not less than 50μm based on total volume of microencapsulated particles: 30.2% byvolume).

Then, efficacy of the insect growth regulating composition of thepresent invention will be shown by Test Examples.

TEST EXAMPLE 1

An insect growth regulating composition to be tested was diluted withwater so that a pyriproxyfen concentration became 1 ppm to prepare atest solution. A pumpkin (fruit) was immersed into the test solution for30 seconds, and air-dried. Egg masses (200 to 300 eggs) ofPseudaulacaspis pentagons were placed on two sites of this pumpkin, andallowed to develop in a room at 25° C. for 25 days. Thereafter, thenumber of male cocoons (male prepupae) of Pseudaulacaspis pentagonsproduced on the test pumpkin was counted.

A pumpkin which had not treated with a drug was subjected to the similartest and, by taking the number of male cocoons of Pseudaulacaspispentagons produced on the non-treated pumpkin as 100, a ratio of thenumber of male cocoons of Pseudaulacaspis pentagons produced on thetreated pumpkin was calculated to obtain insecticidal effect. Theresults are shown in Table 1. TABLE 1 Insecticidal effect PreparationExample 1 A Preparation Example 4 A Reference Preparation C Example

In Table, the insecticidal effect is represented by the followingcriteria:

-   A: The number of male cocoons of the treated pumpkin is less than    40% of the number of male cocoons of the non-treated pumpkin.-   B: The number of male cocoons of the treated pumpkin is 40 to 50% of    the number of male cocoons of the non-treated pumpkin.-   C: The number of male cocoons of the treated pumpkin is more than    50% of the number of male cocoons of the non-treated pumpkin.

TEST EXAMPLE 2

A cabbage seedling planted in a plastic cup was placed for 24 hours intoa net cage in which a number of Bemisia argentifolii inhabited, andBemisia argentifolii was allowed to lay eggs on the cabbage seedling.Thereafter, the cabbage seedling was removed from the net cage, and oneleaf of cabbage was taken by cutting.

On the other hand, an insect growth regulating composition to be testedwas diluted with water so that a pyriproxyfen concentration became 1 ppmto prepare a test solution. The leaf of cabbage was immersed into thetest solution for 30 seconds, air-dried, and allowed to develop in aroom at 25° C. for 8 days. Thereafter, the numbers of hatched eggs andunhatched eggs were investigated, and an ovicidal rate was calculated.Each of the insect growth regulating compositions of the presentinvention prepared in Preparation Examples 1 to 4 had an ovicidal rateof 90% or higher.

As described hereinabove, the insect growth regulating composition ofthe present invention is useful for controlling insect pests.

1. A microencapsulated insect growth regulating composition, whichcomprises an insect growth regulating active ingredient encapsulated ina wall formed of polyurethane or polyurea, having an average particlediameter of 1 to 40 μm, a wall thickness of 0.005 to 0.5 μm, and a ratioof a wall thickness/an average particle diameter of 0.0003 to 0.003,wherein a volume ratio of microencapsulated particles having a particlediameter of not less than 50 μm is not more than 20% by volume based ona total volume of microencapsulated particles.
 2. The insect growthregulating composition according to claim 1, wherein the insect growthregulating active ingredient is an insect juvenile hormone-likecompound.
 3. The insect growth regulating composition according to claim1, wherein the insect growth regulating active ingredient is4-phenoxyphenyl 2-(2-pyridyloxy)propyl ether.
 4. Use of an insect growthregulating composition according to claim 1 for controlling an insectpest.
 5. A method for controlling an insect pest comprising applying aneffective amount of an insect growth regulating composition according toany one of claim 1 to 3 directly to an insect pest or to a place wherean insect pest inhabits.